So, basically, Back to My Mac automatically subscribes you to a dyndns service with which you can’t customize the user name (well, you could rename your computer). Granted, Back to My Mac involves more obvious security risks than this (like the fact that there’s only a tiny .Mac password protecting your computer from being controlled by the whole internet, and most users don’t realize the importance of strong passwords), but I still think it’s a weird choice. Well, it’s not like Apple has a history of caring much about security.